Recently, most motorcycles are possessed of automatic transmission function. As regard to the automatic transmission mechanism of motorcycles, centrifugal clutches are mainly used as elements for power transmission. When the engine of a motorcycle is driven and the rotational speed of the engine is gradually increasing, the clutch rotates via the pulley driving and the detent block of the clutch is thrown outwards. The lining on the external surface of the detent block will be in touch with the internal surface of the frame of a driven disc, and consequently power is transmitted to a driven axis to drive vehicle wheels. When the rotational speed of the engine decreases, the power transmission is stopped as a result that the detent block is pulled inward by the extension spring.
During the time when the detent block is moved, its movement is unstable and will lead to unstable power transmission because of the material characteristics of the detent block. Moreover, the radial force that moves outwards the detent block of the conventional clutch is weaker, which will result in the insufficient strength of the engagement between the detent block and the internal surface of the frame of the driven disc. Consequently, it takes more time and requires higher rotational speed of the engine to rotate the driven disc synchronously. Besides, it takes more time to establish the connection between the lining and the frame of the driven disc. In other words, the lining will rub against the frame of the driven disc for a longer time, which will scorch and degenerate the lining and speed up its abrasion.
Please refer to FIG. 6 showing an improved clutch designed for overcoming above shortcomings. The improved clutch comprises a base having a driving disc “a” and a linked disc “b”. Relative to the internal surface of each indent detent block “c”, the driving disc “a” is provided with a plurality of limiting parts “d” in shape of axial pin passing through the curved slotted holes provided on the linked disc “b”. Besides, the driving disc “a” is provided on the body thereof with a plurality of slots “e”. The linked disc “b” is provided on the body thereof with slot openings “f” corresponding to the slots “e”. Moreover, an elastic piece “g” is provided in the corresponding slot “e” of the deriving disc “a” and the slot opening “f” of the linked disc “b”. Consequently, the linked disc “b” can be driven by the driving disc “a”. Furthermore, the linked disc “b” is pivotally connected with each detent block “c”. Each detent block “c” has a V-shape slot “h” on the internal surface thereof and one axial-pin-shape limiting part “d” is located in the V-shape slot “h”. Thereby, when the base is in accelerated rotation and the linked disc “b” bears so strong rotational resistance that the deformation strength of the elastic piece “g” is insufficient, the elastic piece “g” will be deformed. As a result, the driving disc “a” and the linked disc “b” will move in opposite directions and the axial-pin-shape limiting part “d” will move along the oblique surface “i” in the V-shape slot “h”. Accordingly, the lining “j” can be firmly attached to the internal surface of the frame “k” of the driven disc.
By this way, not only can the power transmission be rendered more smooth and stable, but also less time is taken for the lining to rub against the frame of the driven disc. Consequently, the abrasion of the lining can be reduced and lifetime lengthened as well. However, this kind of clutch as a whole has a quite complicated structure, which will increase the manufacturing and assembling cost and will make the maintenance difficult.
In order to overcome above shortcomings and provide a clutch having a unique structure different from conventional ones, inventor had the motive to study and develop the present invention. After hard research and development, the inventor provides a clutch with high binding ability, which has simple structure and lower manufacturing cost and maintenance expense.